Properties of triangles and the interior and exterior angles of triangles

What you need to learn in this topic

1. Recognise and list geometric properties of various types of triangles. Hence classify triangles based on geometric properties.
2. Make and verify conjectures about (i) the sum of interior angles, (ii) the sum of interior angle and adjacent exterior angle, (iii) the relation between exterior angle and the sum of the opposite interior angles of a triangle.
3. Solve problems involving triangles.